Pat Mullarky mentioned that his D/A "exposed" pump was noisy. That
is a late model pump, but wasn't a "cheap" version, and would make just
as much noise if it were boxed up. For gosh sake, don't replace it with
a suction box! A Duo-Art  would be too loud, even if you could
completely silence the suction box. In D/A music, everything is
controlled "blindly" by the roll, based on the capacity and
characteristics of the instrument, and this revolves around the pump.
Concert grands played louder, simply to take advantage of the large
piano and the large hall, so they could run the pump faster and get
away with it. However, that only perhaps added 50% or so to the power.
A suction box would probably provide an order of magnitude more volume
of air, but the closed head pressure could not get up to concert
pressures like the D/A positive displacement pump can.

   There are a lot of reasons those pumps can get noisy, but usually it
is caused by the linkage and the crank bushings. You have to be sure
they are true and tight, but rotate freely, and I suggest using JAX
MagnaPlate 5 spray can grease on the rod ends. The original grease is
no longer available. It was modelT wheel axle grease which was loaded
with graphite. You can't even find long fiber grease anymore.

   Another cause of noise is failure to replace the flap valves and
seats, and to make sure the flap springs are pulled. If you have a
partially dry-rotted flap seat ciphering twice as much as another one,
then you have a dynamic imbalance which causes the wheel to speed up
and slow down. That makes a thumping noise.

Craig B.